<?php

// 数据库连接类
class DB
{
    //私有的属性
    private static $dbcon = false;
    public $host;
    private $port;
    public $user;
    public $pass;
    private $db;
    private $charset;
    private $link;

    //私有的构造方法
    private function __construct($host, $user, $pass, $db)
    {
        $this->host = '';
        $this->port = '3306';
        $this->user = '';
        $this->pass = '';
        $this->db = '';
        $this->charset = 'utf8';
        //连接数据库
        $this->db_connect();
        //选择数据库
        $this->db_usedb();
        //设置字符集
        $this->db_charset();
    }

    //连接数据库
    private function db_connect()
    {
        $this->link = mysqli_connect($this->host, $this->user, $this->pass, '', $this->port);
        if (!$this->link) {
            echo "数据库连接失败<br>";
            echo "错误编码" . mysqli_errno($this->link) . "<br>";
            echo "错误信息" . mysqli_error($this->link) . "<br>";
            exit;
        }
    }

    //设置字符集
    private function db_charset()
    {
        mysqli_query($this->link, "set names {$this->charset}");
    }

    //选择数据库
    private function db_usedb()
    {
        mysqli_query($this->link, "use {$this->db}");
    }

    //私有的克隆
    private function __clone()
    {
        die('clone is not allowed');
    }

    //公用的静态方法
    public static function getIntance()
    {
        if (self::$dbcon == false) {
            self::$dbcon = new self;
        }
        return self::$dbcon;
    }

    //执行sql语句的方法
    public function query($sql)
    {
        $res = mysqli_query($this->link, $sql);
        if (!$res) {
            echo "sql语句执行失败<br>";
            echo "错误编码是" . mysqli_errno($this->link) . "<br>";
            echo "错误信息是" . mysqli_error($this->link) . "<br>";
        }
        return $res;
    }

    //获得最后一条记录id
    public function getInsertid()
    {
        return mysqli_insert_id($this->link);
    }

    /**
     * 查询某个字段
     * @param
     * @return string or int
     */
    public function getOne($sql)
    {
        $query = $this->query($sql);
        return mysqli_free_result($query);
    }

    //获取一行记录,return array 一维数组
    public function getRow($sql, $type = "assoc")
    {
        $query = $this->query($sql);
        if (!in_array($type, array("assoc", 'array', "row"))) {
            die("mysqli_query error");
        }
        $funcname = "mysqli_fetch_" . $type;
        return $funcname($query);
    }

    //获取一条记录,前置条件通过资源获取一条记录
    public function getFormSource($query, $type = "assoc")
    {
        if (!in_array($type, array("assoc", "array", "row"))) {
            die("mysqli_query error");
        }
        $funcname = "mysqli_fetch_" . $type;
        return $funcname($query);
    }

    //获取多条数据，二维数组
    public function getAll($sql)
    {
        $query = $this->query($sql);
        $list = array();
        while ($r = $this->getFormSource($query)) {
            $list[] = $r;
        }
        return $list;
    }

    public function selectAll($table, $where, $fields = '*', $order = '', $skip = 0, $limit = 1000)
    {
        if (is_array($where)) {
            foreach ($where as $key => $val) {
                if (is_numeric($val)) {
                    $condition = $key . '=' . $val;
                } else {
                    $condition = $key . '=\"' . $val . '\"';
                }
            }
        } else {
            $condition = $where;
        }
        if (!empty($order)) {
            $order = " order by " . $order;
        }
        $sql = "select $fields from $table where $condition $order limit $skip,$limit";
        $query = $this->query($sql);
        $list = array();
        while ($r = $this->getFormSource($query)) {
            $list[] = $r;
        }
        return $list;
    }

    /**
     * 定义添加数据的方法
     * @param string $table 表名
     * @param string orarray $data [数据]
     * @return int 最新添加的id
     */
    public function insert($table, $data)
    {
        //遍历数组，得到每一个字段和字段的值
        $key_str = '';
        $v_str = '';
        foreach ($data as $key => $v) {
            //  if(empty($v)){
            //   die("error");
            // }
            //$key的值是每一个字段s一个字段所对应的值
            $key_str .= $key . ',';
            $v_str .= "'$v',";
        }
        $key_str = trim($key_str, ',');
        $v_str = trim($v_str, ',');
        //判断数据是否为空
        $sql = "insert into $table ($key_str) values ($v_str)";
//        var_dump($sql);exit;
        $this->query($sql);
        //返回上一次增加操做产生ID值
        return $this->getInsertid();
    }

    /*
     * 删除一条数据方法
     * @param1 $table, $where=array('id'=>'1') 表名 条件
     * @return 受影响的行数
     */
    public function deleteOne($table, $where)
    {
        if (is_array($where)) {
            foreach ($where as $key => $val) {
                $condition = $key . '=' . $val;
            }
        } else {
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

    /*
    * 删除多条数据方法
    * @param1 $table, $where 表名 条件
    * @return 受影响的行数
    */
    public function deleteAll($table, $where)
    {
        if (is_array($where)) {
            foreach ($where as $key => $val) {
                if (is_array($val)) {
                    $condition = $key . ' in (' . implode(',', $val) . ')';
                } else {
                    $condition = $key . '=' . $val;
                }
            }
        } else {
            $condition = $where;
        }
        $sql = "delete from $table where $condition";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }

    /**
     * [修改操作description]
     * @param [type] $table [表名]
     * @param [type] $data [数据]
     * @param [type] $where [条件]
     * @return [type]
     */
    public function update($table, $data, $where, $limit = 0)
    {
        //遍历数组，得到每一个字段和字段的值
        $str = '';
        foreach ($data as $key => $v) {
            $str .= "$key='$v',";
        }
        $str = rtrim($str, ',');
        if (is_array($where)) {
            foreach ($where as $key => $val) {
                if (is_array($val)) {
                    $condition = $key . ' in (' . implode(',', $val) . ')';
                } else {
                    $condition = $key . '=' . $val;
                }
            }
        } else {
            $condition = $where;
        }

        if (!empty($limit)) {
            $limit = " limit " . $limit;
        } else {
            $limit = '';
        }
        //修改SQL语句
        $sql = "update $table set $str where $condition $limit";
        $this->query($sql);
        //返回受影响的行数
        return mysqli_affected_rows($this->link);
    }
}

?>